Performance of Ontario’s CANDU nuclear generating stations in 2022

By: Donald Jones, retired nuclear industry engineer, 2023 June 19

The raw performance data for 2022 are taken from the Power Reactor Information System (PRIS) database of the International Atomic Energy Agency (IAEA). Note that the Load Factor term used in the PRIS database has the same meaning as Capacity Factor (CF). CFs are based on the (net) Reference Unit Power and on the (net) Electricity Supplied, as defined in the PRIS database. 

The performance of some of Ontario’s nuclear generating stations is affected by the surplus baseload generation (SBG) in the province. Some nuclear units see electricity output reductions during periods of SBG. This means the CFs are not a true performance indicator for those units (reference 1). A better metric of performance in these cases would be the Unit Capability Factor (UCF – used by Ontario Power Generation and by Bruce Power). The Energy Availability Factor (EAF) is another performance indicator and is shown in the PRIS database. The EAF adjusts the available energy generation for energy losses attributed to plant management, planned and unplanned, and for external energy losses beyond the control of plant management while the UCF only includes energy losses attributed to plant management and excludes the external losses beyond control of plant management like load cycling/load following, grid failures, earthquakes, cooling water temperature higher than reference temperature, floods, lightning strikes, labour disputes outside the plant etc. For a more complete discussion of UCF, EAF and CF see references 2 and 3.

CANDU 6 Performance in 2022

By: Donald Jones, retired nuclear industry engineer, 2023 June 13

History

The two lead CANDU 6 projects were Gentilly 2 in Quebec and Point Lepreau in New Brunswick and these were quickly followed by Embalse in Argentina and Wolsong, now Wolsong 1, in South Korea and all came into service in the early to mid 1980s. These can be regarded as the first tranche of CANDU 6 build.

The second tranche of CANDU 6 units came with Wolsong 2, 3 and 4 in South Korea, Cernavoda 1 and 2 in Romania, and Qinshan 3-1 and 3-2 in China (the other units at Qinshan site are not CANDU), all entering service between 1996 to 2007. Each of the second tranche CANDU 6 units incorporate lessons learned from operation of the earlier units with changes to meet latest regulatory codes and standards.

Load-cycling and load-following, a quick explanation

By: Donald Jones, retired nuclear industry engineer, 2021 Feb. 14

 

Rather than lump all power changes on a grid as load-following, previous articles in this series (The Don Jones Articles) have used the terms load-cycling and load-following. There is a difference.
 
Loads on the electricity grid are generally lower at night than during the day. Power generating units that have planned shutdowns overnight, or go to very low outputs, are load-cycling. In Ontario there are many days when there is a surplus of generation largely from wind and solar generation. To help mitigate this surplus baseload generation one or more nuclear units at Bruce Power will load-cycle down using steam bypass. Typically, on instructions from the grid operator (in Ontario, the Independent Electricity System Operator – IESO) Bruce units would perform a gradual reduction in electrical output of up to 300 MW per unit over a one to two hour period then hold at reduced output for the required length of time, usually several hours, before gradually increasing output over one to two hours. The slow power change is to reduce the thermal stresses on the thick walled components of the steam turbine. Much faster power changes can be made if demanded.
 
During the day the demand on the grid varies more than at night, increasing in the morning, varying during the day, reaching a maximum at dinner time, and then decreasing in the evening. Unpredictable wind and solar generation on the grid (negative load) adds to this variation day and night. To meet this changing load some generating units on the grid have to make frequent changes to their power output (see below).

Coexistence of nuclear with renewables on electricity grid

by: Don Jones, retired nuclear industry engineer, 2020 Sept.14

There are opposing views on whether nuclear and non-hydro renewable energy – variable intermittent renewable energy (VIRE) like wind and solar – can coexist on an electricity grid.
We have this now typical view from Duke Energy (Ref.1), “More importantly, Duke Energy’s plan follows an emerging trend that acknowledges a clean energy economy is only possible with all carbon-free technologies working together. As more companies and policymakers look for solutions to our climate challenges, we must create a pathway to ensure nuclear, wind, solar and other carbon-free technologies successfully exist together.”

Duke’s statement contradicts the view expressed in the oft quoted, , “If someone declares publicly that nuclear power would be needed in the baseload because of fluctuating energy from wind or sun in the grid, he has either not understood how an electricity grid or a nuclear plant operates, or he consciously lies to the public. Nuclear energy and renewable energies cannot be combined “– Siegmer Gabriel (former Federal Environment Minister of Germany).

Can they coexist? Not at present time, not without help from gas, coal or hydro to provide the load-following capability.

In Ontario VIRE does not have priority over nuclear. Available VIRE is manoeuvred before nuclear is manoeuvred and if necessary curtailed completely.  Presently the CANDU reactors on the Ontario grid do not load-follow (Ref. 2) so to maintain grid stability course power adjustments are made by bypassing steam on one or more of the eight CANDU units of Bruce Power (load-cycling) and more frequent power adjustments (load-following) are made by the hydro generators and/or the combined cycle gas turbine (CCGT) units. Even without VIRE it would not be possible to have a stable Ontario grid without the load-following and frequency control capability provided by the hydro and/or gas generators.

CANDU cousins in India – Performance in 2019

By: Donald Jones, retired nuclear industry engineer, 2020 June 3

Most of India’s nuclear reactors are of the pressurized heavy water reactor (PHWR) type with horizontal pressure tubes, just like the Canadian designed CANDU. In fact the first PHWR (not the first nuclear reactor) in India was the Rajasthan Atomic Power Project (RAPP) unit and was a CANDU designed by Atomic Energy of Canada Limited (AECL) that used the Douglas Point unit in Ontario as reference design but modified to aid localization. RAPP-1 entered commercial operation 1973 December. While RAPP-1 was being constructed the design of RAPP-2 was started. However the detonation of a nuclear device by India in 1974 curtailed completion of the design by AECL and India was on its own as far as nuclear technology was concerned. The design was completed by India and RAPP-2 eventually entered commercial operation in 1981 April. Since those early days India has developed its own indigenous designs of PHWRs with net electrical outputs of 202 MWe, 490 MWe, and 630 MWe. They bear little to no resemblance to Douglas Point. All 17 PHWR units operating in 2019 (excludes RAPP-1 which has been shutdown since 2004) were 202 MWe net (220 MWe gross) except for two 490 MWe net (540 MWe gross) units. There were four 630 MWe net (700 MWe gross) units under construction with none in operation. All PHWR power units, except for RAPP-1, are designed, owned, and operated by Nuclear Power Corporation of India Ltd. Several of the country’s PHWRs have been refurbished for extended life operation. For more detailed information on the Indian nuclear program see, Nuclear Power in India (reference 1).

The performance data are taken from the Power Reactor Information System (PRIS) database of the International Atomic Energy Agency (IAEA). Note that the Load Factor term used in the PRIS database has the same meaning as Capacity Factor (CF). CFs are based on the (net) Reference Unit Power and on the (net) Electricity Supplied, as defined in the PRIS database, so capacities referenced in this article are net electrical MW output. The lifetime, or cumulative, CF is based on the date of commercial operation and will include the outage time if the unit has been refurbished. Only the performance of India’s PHWRs is reviewed in detail but India’s four operating non-PHWR units are mentioned.

Lifetime CFs and some recent annual CFs have suffered because of uranium shortages and India’s technical isolation because of it not being a signatory to the Nuclear Non-Proliferation Treaty. Things eased somewhat with the Nuclear Suppliers’ Group agreement achieved in 2008 but the civil liability law introduced in 2010 has still restricted access to foreign technology. Some units are not under International Atomic Energy Agency (IAEA) safeguards and cannot use imported uranium and domestic uranium is in short supply. All this has affected and may still be affecting plant performance. Even so at the end of 2013 Rajasthan unit 5 held the world record in lifetime CF at 94.4 percent, according to Nuclear Engineering International magazine (PRIS data give 94.9 percent to end of 2013). On 2014 September 6 Rajasthan unit 5 achieved a 765 day continuous run at full power. On 2018 December 31 Kaiga unit 1 was taken offline for maintenance after completing 962 days of unbroken operation since 2016 May 13, a world record, with a CF of 99.3 percent. This shows what good design and good operation/maintenance can accomplish.

Performance of Ontario’s CANDU nuclear generating stations in 2019

By: Donald Jones, retired nuclear industry engineer, 2020 June 3

The raw performance data for 2019 are taken from the Power Reactor Information System (PRIS) database of the International Atomic Energy Agency (IAEA). Note that the Load Factor term used in the PRIS database has the same meaning as Capacity Factor (CF). CFs are based on the (net) Reference Unit Power and on the (net) Electricity Supplied, as defined in the PRIS database. For Ontario, at least, the Energy Availability Factor in the PRIS database can be read as the Unit Capability Factor (reference 1).

The performance of some of Ontario’s nuclear generating stations is affected by the surplus baseload generation (SBG) in the province. Some nuclear units saw electricity output reductions during periods of SBG. This means the CFs are not a true performance indicator for those units (reference 2). A better metric of performance in these cases would be the Unit Capability Factor (UCF – used by Ontario Power Generation and by Bruce Power). The Energy Availability Factor (EAF) is another performance indicator and is shown in the PRIS database. The EAF adjusts the available energy generation for energy losses attributed to plant management, planned and unplanned, and for external energy losses beyond the control of plant management while the UCF only includes energy losses attributed to plant management and excludes the external losses beyond control of plant management like load cycling/load following, grid failures, earthquakes, cooling water temperature higher than reference temperature, floods, lightning strikes, labour disputes outside the plant etc.

For Ontario there should be little significant difference between CF, UCF and EAF for units that do not load cycle (an external energy loss) since other external energy losses will be close to zero. For units that load cycle the UCF will be higher than the EAF and higher than the CF but the EAF should not be significantly different from the CF. For example, going back to 2017 PRIS data, Bruce B unit 7 had a 2017 annual CF of 92.8 percent and an EAF of 96.3 percent. However based on what was just said above this EAF of 96.3 percent must really be a UCF of 96.3 percent and this anomaly will apply to all EAFs given in this article.The UCF and the EAF are based on reference ambient conditions so, unlike the CF, they cannot exceed 100 percent. In some cases the CF can be more than the EAF because the cooling water temperature is lower than the reference temperature and that increases the electrical output of the unit.

CANDU 6 Performance in 2019

By: Donald Jones, retired nuclear industry engineer, 2020 June 2

History

The two lead CANDU 6 projects were Gentilly 2 in Quebec and Point Lepreau in New Brunswick and these were quickly followed by Embalse in Argentina and Wolsong, now Wolsong 1, in South Korea and all came into service in the early to mid 1980s. These can be regarded as the first tranche of CANDU 6 build.

The second tranche of CANDU 6 units came with Wolsong 2, 3 and 4 in South Korea, Cernavoda 1 and 2 in Romania, and Qinshan 3-1 and 3-2 in China (the other units at Qinshan site are not CANDU), all entering service between 1996 to 2007. Each of the second tranche CANDU 6 units incorporate lessons learned from operation of the earlier units with changes to meet latest regulatory codes and standards.

Capacity Factor

The Capacity Factors are taken from the PRIS (Power Reactor Information System) database of the IAEA (International Atomic Energy Agency). Note that the Load Factor term used in the PRIS database has the same meaning as Capacity Factor (CF). Capacity Factors are based on the (net) Reference Unit Power and on the (net) Electricity Supplied figures, as defined in the PRIS database. The Energy Availability Factor (EAF) is another performance indicator and is shown in the PRIS database. The EAF adjusts the available energy generation for energy losses attributed to plant management, planned and unplanned, and for external energy losses beyond the control of plant management. The Unit Capability Factor (UCF), another performance metric, only includes energy losses attributed to plant management and excludes the external losses beyond control of plant management like load cycling/load following, grid failures, earthquakes, cooling water temperature higher than reference temperature, floods, lightning strikes, labour disputes outside the plant etc. The UCF seems a much better indicator of how well the unit is being managed than either CF or EAF but it is not specifically identified in the PRIS database (reference 1). Note that Bruce Power and Ontario Power Generation use UCF as a performance indicator.

Small Modular Reactors in Canada’s future

By: Donald Jones, retired nuclear industry engineer, 2019 December 04

The announcement on 2019 December 01 by the premiers of Saskatchewan, Ontario and New Brunswick about cooperation in the development and deployment of Small Modular Reactors (SMRs) (Ref. 1) should not have come as a total surprise. Ontario Power Generation (OPG) has been working with a Micro Modular Reactor (MMR- a smaller version of a SMR) vendor to assist in getting its design through the pre-licensing vendor design reviews of the Canadian Nuclear Safety Commission (CNSC). Bruce Power and New Brunswick Power have also been working with SMR vendors. There are many (Ref.2) SMR vendors at different stages in the review pipeline of the CNSC with no two reactors being the same. In some cases the design is an improved version of small reactors that have operated successfully in the past but now meeting current design codes and safety regulations in a modular configuration. Small reactors of various capacities and capable of rapid power manoeuvring have been used for many years to power submarines, aircraft carriers (U.S.A) and heavy duty ice breakers (Russia). Small reactors of many different designs are not new but the concept of designing  them for serial construction and collectively to comprise a large nuclear power plant is new.

Ontario’s IESO uses wind and solar to reduce the carbon intensity of its electricity system

By: Donald Jones, retired nuclear industry engineer, 2019 October 15.

Combined Cycle Gas Turbine (CCGT) power plants produce electricity very efficiently with steady state baseload and intermediate load overall efficiencies of over 60 percent for newer units. Most presently operating units would have somewhat lower efficiencies. Unfortunately on most power grids with significant wind and/or solar generation they rarely operate at steady state (reference 1).

Operating CCGT plants at part load and stopping and starting the gas turbine(s) leads to lower plant efficiency and increased emissions of greenhouse gases per megawatt-hour generated as well as wear and tear on the units. Every time a CCGT is warming up gas is being burned while the gas turbine is slowly increasing power and warming up the heat recovery steam generators (HRSG), and the steam turbine when steam becomes available. This increases the heat rate giving higher kg GHG/MWh. If a CCGT had a bypass stack the gas turbine could be delivering power very quickly but at high heat rate (low overall efficiency) since it would be operating simple cycle and giving higher kg GHG/MWh. When increasing power (manoeuvring/ramping) in the operating range the HRSG and steam turbine metal have to be warmed up which takes away gas for no useful power output, increasing kg GHG/MWh.

Ontario has a very low carbon intensity electricity grid averaging 40 g CO2e/kWh. In 2018 more than 93 percent of the electricity generated in Ontario came from non-GHG emitting resources, predominantly nuclear and hydro with some wind and solar. Nuclear provided 61 percent of generation in 2018. There is about 10000 MW of gas-fired and oil-fired generation connected to the transmission grid mostly CCGTs burning natural gas and just under 5000 MW (nameplate capacity) of wind and solar. CCGTs are used to meet peak load demands and provide operational flexibility.

CANDU 6 Performance in 2018

By: Donald Jones, retired nuclear industry engineer, 2019 April 21

History

The two lead CANDU 6 projects were Gentilly 2 in Quebec and Point Lepreau in New Brunswick and these were quickly followed by Embalse in Argentina and Wolsong, now Wolsong 1, in South Korea and all came into service in the early to mid 1980s. These can be regarded as the first tranche of CANDU 6 build.

The second tranche of CANDU 6 units came with Wolsong 2, 3 and 4 in South Korea, Cernavoda 1 and 2 in Romania, and Qinshan 3-1 and 3-2 in China (the other units at Qinshan site are not CANDU), all entering service between 1996 to 2007. Each of the second tranche CANDU 6 units incorporate lessons learned from operation of the earlier units with changes to meet latest regulatory codes and standards.

Capacity Factor

The Capacity Factors are taken from the PRIS (Power Reactor Information System) database of the IAEA (International Atomic Energy Agency). Note that the Load Factor term used in the PRIS database has the same meaning as Capacity Factor (CF). Capacity Factors are based on the (net) Reference Unit Power and on the (net) Electricity Supplied figures, as defined in the PRIS database. The Energy Availability Factor (EAF) is another performance indicator and is shown in the PRIS database. The EAF adjusts the available energy generation for energy losses attributed to plant management, planned and unplanned, and for external energy losses beyond the control of plant management. The Unit Capability Factor (UCF), another performance metric, only includes energy losses attributed to plant management and excludes the external losses beyond control of plant management like load cycling/load following, grid failures, earthquakes, cooling water temperature higher than reference temperature, floods, lightning strikes, labour disputes outside the plant etc. The UCF seems a much better indicator of how well the unit is being managed than either CF or EAF but it is not specifically identified in the PRIS database (reference 1). Note that Bruce Power and Ontario Power Generation use UCF as a performance indicator.

CANDU 6 Units

Point Lepreau, New Brunswick, Canada. At the end of 2018 the lifetime CF since start of commercial operation in 1983 was 70.9 percent, including the refurbishment outage, and the annual CF for 2018 was 84.6 percent (EAF 84.5 percent).